Kelly et al. (NHANES DXA)

Full name: Body composition reference values from NHANES DXA data
Year: 2009
Sample size: n = 13.1K
Population: US adults aged 20-85 from NHANES 1999-2004, measured by DXA (dual-energy X-ray absorptiometry). Separate analyses for White, Black, and Mexican American groups.
Study type: Cross-sectional population survey (nationally representative)
Link: DOI: 10.1371/journal.pone.0007038

About this reference

Kelly and colleagues analysed dual-energy X-ray absorptiometry (DXA) body composition data from NHANES 1999-2004 and published LMS curve parameters (median, standard deviation and skewness) for percent body fat by age and sex in supplementary Table S2, separately for non-Hispanic White, non-Hispanic Black and Mexican American adults. FitnessNorms used the White curve for its body fat percentage pages until October 2026. Since October 2026 the body-composition pages use an all-adult derivation from the same NHANES scans instead (NHANES 1999-2004 DXA); this paper is cited as a comparison and for its fat mass index classification ranges.

Known limitations

Measured by DXA (Hologic scanners, NHANES calibration); DXA, bioelectrical-impedance, and skinfold methods are not directly interchangeable and can differ by several percentage points
Curves are fitted separately by ethnic group; there is no pooled all-adult curve
The paper publishes LMS parameters at single ages (20, 25, ... 85), not percentile tables
US population only; Americans tend to have 5-10 percentage points higher body fat than European or Asian populations at the same age and BMI
Cross-sectional design means values reflect population averages, not individual changes over time